1. Field of the Invention
The present invention relates to a method for preparing metal oxide nanoparticles and metal oxide nanoparticles prepared thereby, and more particularly, to a method for preparing metal oxide nanoparticles by dipping an anode formed of a metal forming oxide and a cathode in an electrolyte solution containing a halogen salt, and applying voltage to the anode and the cathode, and metal oxide nanoparticles prepared thereby.
2. Description of the Related Art
Among functional materials synthesized in a nano-scale, metal oxide nanoparticles are a material that is most likely to be applicable to industry. Since the metal oxide nanoparticles have physically, chemically and electrically intrinsic characteristics, the metal oxide nanoparticles may be applied to various fields.
Up to now, methods, such as a co-precipitation method, hydrolytic and non-hydrolytic sol-gel methods, a microemulsion method, a hydrothermal/solvothermal method, a microwave, a thermal decomposition, a chimie douce, a sonochemical method, and template syntheses, have been used for synthesizing the metal oxide nanoparticles.
The aforementioned typical nanoparticle synthesizing methods have inherent disadvantages and limitations. The inherent disadvantages and limitations are that an expensive precursor is required, a process is performed under high temperature and high pressure conditions, a surfactant is required (where there is a possibility of contamination due to the surfactant), a long time is taken, or a complex preparing process having a multi-stage is required. For preparing specific metal oxide, the methods may be often used in combination with each other.
Meanwhile, a typical technology related to a method for preparing metal oxide, for example, Korea Publication Patent No. 10-2004-0048093 discloses a method for preparing metal oxide nanoparticles of which a particle size distribution is mono-dispersed, and metal oxide nanoparticles prepared by the same. In more detail, Korea Publication Patent No. 10-2004-0048093 discloses a method for preparing metal oxide nanoparticles, which includes: a) adding a surfactant into a dispersed organic solvent to prepare a surfactant solution; b) mixing the surfactant solution and a metallic salt solution to prepare a first water-in-oil emulsion; c) mixing the surfactant solution and a base solution to prepare a second water-in-oil emulsion; d) mixing the first water-in-oil emulsion and the second water-in-oil emulsion to react metallic salt and the base solution and to prepare a metal oxide nanoparticle colloid solution; and e) washing, separating and drying the metal oxide nanoparticle colloid solution to obtain metal oxide nanoparticles.
However, the method has a limitation in that a surfactant is used, and a process is complicated.
Therefore, the inventors have studied a method for preparing crystalline metal oxide nanoparticles through a more simple and rapid method that does not use a surfactant, have found a method capable of preparing metal oxide by dipping an anode constituted of a metal wire or a metal sheet and a cathode, in an electrolyte containing halogen salt and applying voltage to the anode and the cathode to oxidize the anode, and eventually completed the present invention.